Mus­ings are thoughts, the thought­ful kind. For the pur­pose of these ar­ti­cles, a-mus­ings are thoughts that might amuse, en­ter­tain and even en­lighten.

Ev­ery­thing is Green these days. As usual, I sup­pose, Shake­speare got it right, but be­fore I go on to ex­pand upon that some­what cryptic re­mark just let me say that Jeal­ousy, the green-eyed mon­ster, is alive and well, ac­cord­ing to the find­ings of a fairly re­cent in­ter­na­tional study. Ap­par­ently, men are mostly jeal­ous about sex­ual ad­ven­tures, while women are jeal­ous about emo­tional at­tach­ments. Whether this is due to en­vi­ron­ment, evo­lu­tion or cul­ture is some­thing ex­perts dis­agree upon.

But why should jeal­ousy be Green? Green is, ad­mit­tedly, a colour as­so­ci­ated with sick­ness, pos­si­bly be­cause peo­ple's skin some­times takes on a slightly yel­low/ green tinge when they are se­ri­ously ill. And Green is also the colour of many un­ripe fruits that might cause stom­ach pains. But other than that, why Green?

But back to the Bard! The phrase was used by, and pos­si­bly coined by, Shake­speare in 1596 to de­note jeal­ousy in The Mer­chant of Venice when he has Por­tia say: How all the other pas­sions fleet to air, As doubt­ful thoughts, and rash-em­braced de­spair, And shud­der­ing fear, and greeneyed jeal­ousy! O love, Be mod­er­ate; al­lay thy ec­stasy, In mea­sure rein thy joy; scant this ex­cess. I feel too much thy bless­ing: make it less, For fear I sur­feit.

Now you could spend the rest of the day try­ing to work out what Por­tia re­ally wanted, but for the mo­ment let it suf­fice that she was not too keen on jeal­ousy and wanted her chap­pie to calm down a bit.

Half a dozen years later, in 1604, Wil­lie still had a thing about Green. In Othello he al­ludes to cats as green-eyed mon­sters in the way that they play with mice be­fore killing them. Lago pro­claims: O, be­ware, my lord, of jeal­ousy; It is the green-eyed mon­ster which doth mock the meat it feeds on; that cuck­old lives in bliss Who, cer­tain of his fate, loves not his wronger; But, O, what damned min­utes tells he o'er who dotes, yet doubts, sus­pects, yet strongly loves!

Clearly, jeal­ousy leads or led to mud­dled think­ing even in the time of good old Bill.

Men tend to be most jeal­ous about their part­ners hav­ing sex with some­one else. It seems that males need to know if their ri­val was good in bed – or bet­ter yet, big­ger. It used to be thought that jeal­ousy in men could also be due to the fact that a man could never be ab­so­lutely cer­tain that a child was re­ally his; of course, DNA test­ing has taken the un­cer­tainty and fun out of on-the-side preg­nan­cies.

Men seem pretty con­fused about their de­sire for a part­ner not to have sex with another man. It seems that men may be up­set by sex be­cause they think it im­plies emo­tional com­mit­ment, although they also be­lieve a woman can be emo­tion­ally in­volved with­out hav­ing sex. Or at least, that's how I read the re­port.

Women are more likely to be up­set about their part­ners form­ing an emo­tional at­tach­ment with some­one else; fe­males want to know if he loves the "other woman". Women are up­set by emo­tional in­fi­delity be­cause they be­lieve that for men it au­to­mat­i­cally means sex. At the same time, women be­lieve that men can have sex with­out com­mit­ment. It may also be pos­si­ble, that the ori­gin of jeal­ousy in women is due to the sub­stan­tial in­vest­ment they make in pro­duc­ing a child; an in­vest­ment that would be “wasted” if their part­ner fell in love with some­one else. On the other hand, many a woman left with a child to take care of with­out pa­ter­nal sup­port might ap­pear to go along with the sit­u­a­tion with a cer­tain equa­nim­ity. She has, af­ter all, “her child”, an at­ti­tude I find quite dis­turb­ing.

And fi­nally, here's some­thing for you to get your teeth into: It seems that the fer­til­ity rate of a coun­try af­fects jeal­ousy. Men in coun­tries with high fer­til­ity rates are very jeal­ous about their part­ners hav­ing sex with oth­ers. Men in coun­tries with lower fer­til­ity rates seem less con­cerned. How women feel about in­fi­delity in in­fer­tile en­vi­ron­ments is not clear.